Parking brake device including pivotable brake lever which extends through aperture of backing plate

ABSTRACT

A parking brake device for a vehicle, including: (a) a backing plate which is fixed to a body of the vehicle such that the backing plate is held substantially perpendicular to an axis of a wheel of the vehicle; (b) first and second arcuate brake shoes which are disposed on one of opposite sides of the backing plate such that the first and second arcuate brake shoes are movable toward and away from each other; (c) a moving mechanism which is positioned between the first and second arcuate brake shoes and which includes a pivotable brake lever, the moving mechanism moving the first and second arcuate brake shoes away from each other when the brake lever is pivoted in a predetermined direction; and (d) an operable member which is connected to the brake lever and which is operable by an operator of the vehicle to pivot the brake lever in the predetermined direction, wherein the brake lever has a connected portion at which the brake lever is connected to the operable member, and wherein the brake lever extends through an aperture which is formed through the backing plate such that the connected portion is positioned on the other of the opposite sides of the backing plate.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates in general to a parking brake device for avehicle. More particularly, this invention is concerned with a parkingbrake device which has provision for facilitating connection of anoperable member such as a parking brake cable, with a member of theparking brake device such as a pivotable brake lever, and which iscapable of generating a braking force with a high ratio of the generatedbraking force with respect to a driving or operating force that isapplied to the operable member.

[0003] 2. Discussion of the Related Art

[0004] There is known a parking brake device for a vehicle, including:(a) a backing plate which is fixed to a body of the vehicle such thatthe backing plate is held substantially perpendicular to an axis of awheel of the vehicle; (b) first and second arcuate brake shoes which aredisposed on one of opposite sides of the backing plate such that thefirst and second arcuate brake shoes are movable toward and away fromeach other; (c) a moving mechanism which is positioned between the firstand second arcuate brake shoes and which includes a pivotable brakelever, the moving mechanism moving the first and second arcuate brakeshoes away from each other when the brake lever is pivoted in apredetermined direction; and (e) an operable member which is connectedto the brake lever and which is operable by an operator of the vehicleto cause the brake lever to be pivoted in the above-describedpredetermined direction.

[0005]FIGS. 6 and 7 illustrate an example of the above-described knownparking brake device in the form of a so-called “drum-in-disk brakeassembly” including a disk brake and a drum brake which is built in thedisk brake. In such a drum-in-disk brake assembly, the disk brake servesas a service brake to be activated mainly during running of the vehicle,while the drum brake serves as a parking brake. This illustrateddrum-in-disk brake assembly is designed to be provided in an automotivevehicle, for braking a right wheel of the vehicle. FIG. 6 is a frontelevational view of the brake. A forward direction of the vehiclecorresponds to the rightward direction as seen in FIG. 6. FIG. 7 is across sectional view taken along line 7-7 of FIG. 6. The brake includesa backing plate 10 which is fixed to a body of the vehicle such that thebacking plate 10 is held substantially perpendicular to an axis of awheel (not shown) of the vehicle; first and second arcuate brake shoes12, 14 which are disposed substantially symmetrically with each otheralong respective circumferential portions of a periphery of the backingplate 10; and hold-down devices 16, 18 which hold the respective twoarcuate brake shoes 12, 14 such that the two arcuate brake shoes 12, 14are movable toward and away from each other. The brake shoes 12, 14 havea first pair of adjacent portions each of which is provided by a lowerend portion (as seen in FIG. 6) of the corresponding brake shoe 12, 14,and a second pair of adjacent portions each of which is provided by anupper end portion (as seen in FIG. 6) of the corresponding brake shoe12, 14. A toggle-type moving mechanism 20 and a tension coil spring 22(which serves as a return spring) are provided between the upper endportions of the respective brake shoes 12, 14, and extend substantiallyin the horizontal direction as seen in FIG. 6. A strut 24 and a tensioncoil spring 24 are provided between the lower end portions of therespective brake shoes 12, 14, and extend substantially in thehorizontal direction. The strut 24 is longitudinally expansible andcontractible by means of screw connection of two component partsthereof, so that the length of the strut 24 is adjusted by a shoe-wearcompensating mechanism.

[0006] As shown in FIG. 7, the moving mechanism 20 includes a connectingpin 30 which is held substantially parallel to the backing plate 10, andfirst and second levers 32, 34 which are connected at their respectiveend portions with each other through the connecting pin 30 such that thefirst and second levers 32, 34 are pivotable relative to each other. Thefirst lever 32 consists of two metallic plates which are superposed oneach other. The two metallic plates are held in close contact with eachother in the end portion of the first lever 32 at which the first lever32 is connected with the second lever 34, and are spaced apart from eachother by a predetermined distance in the other end portion of the firstlever 34. The first lever 32 has, in the end portion in which the twometallic plates are held in close contact with each other, an engagedportion (recessed portion) 36 which is held in engagement with the firstbrake shoe 12. The first lever 32 has, in the above-described other endportion in which the two metallic plates are spaced apart from eachother, a cable-engaging portion 38 with which an engaged member 42 of aparking brake cable 40 is engaged. The engaged member 42 consists of acylindrical member or a hexagonal prism member having a diameter largerthan that of the cable 40, and is coaxially fixed to an end of the cable40. The second lever 34 consists of a single metallic plate which isbent so as to take a substantially U shape. The first lever 32 isdisposed inside the second lever 34, namely, interposed between twomutually opposed portions of the second lever 34 which are opposed toeach other as a result of the bending of the single metallic plate. Thetwo mutually opposed portions of the second lever 34 are held in closecontact with each other in the other end portion of the second lever 34which is opposite to the end portion at which the second lever 34 isconnected with the first lever 32 through the connecting pin 30. Thesecond lever 34 has, in this other end portion, an engaged portion(recessed portion) 48 which is held in engagement with the second brakeshoe 14.

[0007] To the second lever 34, there is fixed a plate spring 50 which isbent so as to take a predetermined shape as shown in FIG. 7. The platespring 50 is provided to serve as a guiding member for guiding theengaged member 42 of the cable 40 into engagement with thecable-engaging portion 38 of the first lever 32, and also to prevent theengaged member 42 once engaged with the cable-engaging portion 38, frombeing disengaged from the cable-engaging portion 38. It is noted thatthe first lever 32 serves as the above-described brake lever, and thatthe parking brake cable 40 serves as the operable member.

[0008] The moving mechanism 20 is held in contact with a head portion 52h of each of a plurality of bolts 52 which are provided to fix an anchormember 54 and the backing plate 10 to a carrier (not shown) of thevehicle. Each of the anchor member 54 and the backing plate 10 has anaperture 56 through which the parking brake cable 40 is introduced intothe interior of the drum-in-disk brake assembly. The first lever 32 ispositioned relative to the backing plate 10 such that the cable-engagingportion 38 is substantially aligned with the aperture 56 as viewed in adirection perpendicular to the baking plate 10. In this arrangement, thecable 40 can be connected to the first lever 32, simply introducing theend portion of the cable 40 with the engaged member 42, through theaperture 56 from the exterior of the drum-in-disk brake assembly (i.e,from the upper side of the backing plate 10 as seen in FIG. 7) to theinterior of the drum-in-disk brake assembly. That is, the engaged member42, fixed to the introduced end portion of the cable 40, is guided bysliding contact with the plate spring 50 so as to be brought intoengagement with the cable-engaging portion 38 of the first lever 32.

[0009] When the parking brake cable 40 thus connected to thecable-engaging portion 38 is pulled by an operation of anoperator-controlled operation member (e.g., an operating lever) which isprovided in a passengers' compartment of the vehicle, in a directionindicated by the arrow F, i.e., in the upward direction as seen in FIG.7, the first lever 32 is pivoted about the connecting pin 30 in thecounter-clockwise direction as seen in FIG. 7, whereby the first brakeshoe 12 is displaced in the outward direction, i.e., in the leftwarddirection as seen in FIG. 7. The leftwardly displaced first brake shoe12 is forced onto a disk rotor (not shown), for thereby generating abraking force for braking the wheel rotating with the disk rotor. Theconnecting pin 30 is displaced relative to the first brake shoe 12 inthe rightward direction as shown in FIG. 7, by a reaction force whichresists the outward displacement of the first brake shoe 12. Therightward displacement of the connecting pin 30 causes the second lever34 to be displaced in the rightward direction, whereby the second brakeshoe 14 is displaced in the outward direction, i.e., in the rightwarddirection. The rightwardly displaced second brake shoe 14 is forced ontothe disk rotor, for thereby generating a braking force for braking thewheel rotating with the disk rotor. The disk rotor consists of a diskportion and a cylindrical drum portion which is positioned radiallyinwardly of the disk portion. The outwardly displaced first and secondbrake shoes 12, 14 are forced onto an inner circumferential surface ofthe cylindrical drum portion of the disk rotor. It is noted that a dustcover 58 is fixed to the backing plate 10 so as to extend radiallyoutwardly from the periphery of the backing plate 10.

[0010] The conventional parking brake device constructed as describedabove is not necessarily satisfactory in cost of manufacture of thebrake device, due to the provision of the guiding member in the form ofthe plate spring 50 which leads to an increase in the number of therequired components of the brake device. Further, the plate spring 50does not satisfactorily facilitate an operation for bringing the parkingbrake cable 40 into engagement with the cable-engaging portion 38 of thefirst lever 32. Still further, in the above-described parking brakedevice in which the parking brake cable 40 has to be pulled in thedirection substantially perpendicular to the backing plate 10, the firstand second levers 32, 34 are pressed against a supporting portion in theform of the head portions 52 h of the bolts 52 which serves to supportthe moving mechanism 60, whereby friction forces acting between thelevers 32, 34 and the head portions 52 h are increased. The slidingmovements of the first and second levers 32, 34 relative to the headportions 52 h are resisted by the increased friction forces, therebyresulting in an undesirable reduction in a ratio of the generatedbraking force with respect to a driving or operating force which isapplied to the operable member.

SUMMARY OF THE INVENTION

[0011] It is therefore an object of the present invention to provide aparking brake device which has provision for enabling an operable membersuch as a parking brake cable to be easily connected to a brake leverwithout an additional member such as a guiding member, and which iscapable of generating a braking force with a high ratio of the generatedbraking force with respect to a driving or operating force which isapplied to the operable member. This object may be achieved according toany one of first through ninth aspects of this invention which aredescribed below.

[0012] The first aspect of the invention provides a parking brake devicefor a vehicle, comprising: (a) a backing plate which is fixed to a bodyof the vehicle such that the backing plate is held substantiallyperpendicular to an axis of a wheel of the vehicle; (b) first and secondarcuate brake shoes which are disposed on one of opposite sides of thebacking plate such that the first and second arcuate brake shoes aremovable toward and away from each other; (c) a moving mechanism which ispositioned between the first and second arcuate brake shoes and whichincludes a pivotable brake lever, the moving mechanism moving the firstand second arcuate brake shoes away from each other when the brake leveris pivoted in a predetermined direction; and (d) an operable memberwhich is connected to the brake lever and which is operable by anoperator of the vehicle to pivot the brake lever in the predetermineddirection, wherein the brake lever has a connected portion at which thebrake lever is connected to the operable member, and wherein the brakelever extends through an aperture which is formed through the backingplate such that the connected portion is positioned on the other of theopposite sides of the backing plate.

[0013] The second aspect of the invention provides a parking brakedevice for a vehicle, comprising: (a) a backing plate (10) which isfixed to a body of the vehicle such that the backing plate is heldsubstantially perpendicular to an axis of a wheel of the vehicle; (b)first and second arcuate brake shoes which are disposed on one ofopposite sides of the backing plate such that the first and secondarcuate brake shoes are movable toward and away from each other; (c) amoving mechanism including first and second levers which are engagedwith the first and second arcuate brake shoes, and which are connectedwith each other through a connecting pin that is held substantiallyparallel to the backing plate, such that the first and second levers arepivotable relative to each other about the connecting pin, the movingmechanism moving the first and second arcuate brake shoes away from eachother when the first lever is pivoted about the connecting pin in apredetermined direction; and (d) an operable member which is connectedto the first lever and which is operable by an operator of the vehicleto pivot the first lever about the connecting pin in the predetermineddirection, wherein the first lever has a connected portion at which thefirst lever is connected to the operable member, and wherein the firstlever extends through an aperture which is formed through the backingplate such that the connected portion is positioned on the other of theopposite sides of the backing plate.

[0014] According to the third aspect of the invention, the parking brakedevice defined in the second aspect of the invention further comprises acover which is made of an elastic material, and which covers a spacebetween the first lever and the aperture while permitting the firstlever to be pivoted about the connecting pin, wherein the cover has anengageable portion which is engageable with the first lever, forlimiting a movement of the first lever in a direction perpendicular tothe predetermined direction.

[0015] According to the fourth aspect of the invention, in the parkingbrake device defined in the second or third aspect of the invention, theoperable member is a parking brake cable which is connected at one ofopposite end portions thereof to the first lever and which is connectedat the other of the opposite end portions to an operating lever providedin a passengers' compartment of the vehicle.

[0016] According to the fifth aspect of the invention, in the parkingbrake device defined in any one of the second through fourth aspects ofthe invention, the first lever is engaged at an engaged portion thereofwith the first arcuate brake shoe, and wherein a distance between theconnected portion and the connecting pin is at least five times as largeas a distance between the engaged portion and the connecting pin.

[0017] According to the sixth aspect of the invention, in the parkingbrake device defined in any one of the second through fifth aspects ofthe invention, the operable member applies a force to the first leversuch that the force acts on the first lever in a direction that isinclined with respect to a plane parallel to the the backing plate by anangle of 5°-30° toward a longitudinally-extending center line of thebody of the vehicle.

[0018] According to the seventh aspect of the invention, the parkingbrake device defined in any one of the second through sixth aspects ofthe invention, the operable member applies a tensile force to the firstlever such that the tensile force acts on the first lever in aforce-acting direction that is inclined with respect to a plane parallelto the backing plate by an angle of 5°-30° in such a direction thatcauses the first lever to be forced toward a longitudinally-extendingcenter line of the body of the vehicle when the tensile force is appliedto the first lever by the operable member.

[0019] According to the eighth aspect of the invention, in the parkingbrake device defined in the sixth or seventh aspect of the invention,the connected portion is positioned such that the direction issubstantially perpendicular to a straight line connecting the connectedportion and the connecting pin.

[0020] According to the ninth aspect of the invention, in the parkingbrake device defined in any one of the second through fifth aspects ofthe invention, the operable member applies a force to the first leversuch that the force acts on the first lever in a force-acting directionthat is substantially perpendicular to a plane parallel with the backingplate.

[0021] In the above-described parking brake device constructed accordingto the first aspect of the invention, the brake lever extends throughthe aperture of the backing plate such that the connected portion of thebrake lever is positioned on the above-described other of the oppositesides of the backing plate, namely, such that the connected portion ofthe brake lever projects from the aperture towards the body of thevehicle. This arrangement facilitates an operation for connecting theoperable member to the brake lever, and also makes it possible toeliminate a conventionally required guiding member, leading to reductionin the number of the required components of the parking brake device andconsequent reduction in the cost of manufacture of the device. Further,the positioning of the connected portion of the brake lever on theabove-described other of the opposite sides of the backing plate iseffective to increase a degree of freedom in determining a force-actingdirection in which a driving or operating force applied through theoperable member acts on the brake lever, thereby making it possible toinstall the parking brake device in various types of vehicles, and alsoto increase a ratio of a braking force (generated by the parking brakedevice) with respect to the operating or driving force (applied to theoperable member). The increased ratio of the braking force with respectto the driving force means that a relatively large braking force can begenerated by even a relatively small operating or driving force appliedto the operable member.

[0022] In the above-described parking brake device constructed accordingto the second aspect of the invention, the first lever extends throughthe aperture of the backing plate such that the connected portion of thefirst lever is positioned on the above-described other of the oppositesides of the backing plate, namely, such that the connected portion ofthe second lever projects from the aperture towards the body of thevehicle. This arrangement facilitates an operation for connecting theoperable member to the brake lever, and also makes it possible toeliminate a conventionally required guiding member, leading to reductionin the number of the required components of the parking brake device andconsequent reduction in the cost of manufacture of the device. Further,the positioning of the connected portion of the first lever on theabove-described other of the opposite sides of the backing plate iseffective to increase a degree of freedom in determining theforce-acting direction in which the driving or operating force appliedthrough the operable member acts on the first lever, thereby making itpossible to install the parking brake device in various types ofvehicles. Where the force-acting direction is adapted to be close to thedirection in which the first and second arcuate brake shoes are movableaway from each other, it is possible to reduce friction force actingbetween the moving mechanism and the supporting portion which supportsthe moving mechanism, thereby increasing the above-described ratio ofthe braking force with respect to the driving force. The increased ratioof the braking force with respect to the driving force means that arelatively large braking force can be generated by even a relativelysmall driving force, e.g., a relatively small operating force applied toan operator-controlled operation member (e.g., an operating lever) whichis provided in a passengers' compartment of the vehicle. It is notedthat this second aspect of the invention corresponds to one embodiedform of the above-described first aspect of the invention, and that thefirst lever defined in this second aspect of the invention correspondsto the brake lever defined in the first aspect of the invention.

[0023] In the above-described parking brake device constructed accordingto the third aspect of the invention, the engageable portion is formedintegrally with the other portion of the cover which covers the spacebetween the first lever and the aperture, so that backlash movement ofthe first lever in the direction perpendicular to the above-describedpredetermined direction can be limited by engagement of the engageableportion with the first lever. In this arrangement, it is possible toprevent abutting contact of the first lever with an edge of theaperture, i.e., abutting contact of metallic members with each other,for example, when the vehicle body is vibrated during running of thevehicle. Thus, generation of unpleasant noise which would be caused inthe event of the abutting contact of the metallic members isadvantageously avoided.

[0024] In the above-described parking brake device constructed accordingto the sixth aspect of the invention, the operable member applies atensile or pressing force to the first lever such that the tensile orpressing force acts on the first lever in the force-acting directionwhich is inclined with respect to the plane parallel to the backingplate by the angle of 5°-30° toward the longitudinally-extending centerline of the vehicle body, namely, which is close to the direction inwhich the brake shoes are movable away from each other. This arrangementis effective to increase the above-described ratio of the generatedbraking force with respect to the driving force, whereby a relativelylarge braking force can be generated by even a relatively small drivingforce. Further, since the force-acting direction is inclined withrespect to the above-described plane by at least 5° toward the centerline of the vehicle body, the moving mechanism (including the firstlever) is forced toward the backing plate by a certain amount of force,without the moving mechanism being displaced away from the backing plateupon activation of the parking brake device, i.e., without a risk ofreduction in a braking performance of the parking brake device.

[0025] The principle of the present invention is advantageously applied,particularly, to the parking brake device as defined in the secondaspect of the invention. However, the principle of the invention can beapplied to other various types of parking brake devices such as astrut-type parking brake device in which a brake lever is attached toone of the brake shoes or a strut such that the brake lever is pivotableabout a connecting pin that is substantially perpendicular to thebacking plate so that the brake shoes are moved away from each other bya link mechanism constituted by the brake lever and the strut.

[0026] The parking brake device of the invention is advantageously usedas a drum brake which constitutes a part of a drum-in-disk brakeassembly as shown in FIG. 6, and which serves as a parking brake device.However, the parking brake device of the invention can constitute also apart of a drum brake assembly which functions as a service brake as wellas a parking brake, so that the parking brake device of the inventionprovides the drum brake assembly with a function of the parking brake.Further, while the moving mechanism is held substantially in thehorizontal posture so as to move the generally vertically extendingbrake shoes away from each other in the drum-in-disk brake assembly ofFIG. 6, such arrangements and postures of the moving mechanism and brakeshoes may be modified.

[0027] As described above, in FIG. 7, the first and second levers areconnected at their respective end portions with each other through theconnecting pin such that the first and second levers are pivotablerelative to each other. The first lever is engaged, at the end portionat which the first lever is connected to the second lever through theconnecting pin, with one of the brake shoes. The second lever is engagedat the other end portion with the other of the brake shoes. Sucharrangements of the first and second levers and connecting pin may bemodified, for example, such that the first and second levers extend fromthe connecting pin in respective directions opposite to each other so asto be engaged with the respective brake shoes.

[0028] While the connecting pin connecting the first and second leversis positioned on one of opposite sides of the brake shoe which is remotefrom the backing plate in FIG. 7, the connecting pin may be positionedon the other of the opposite sides of the brake shoe. Further, theparking brake device may include a member which functions as a stopperto prevent the first and second levers from being moved away from thebacking plate.

[0029] It is preferable that each of the first and second levers isconstituted by a single metallic plate or a plurality of metallic platesand that each of the levers is held in substantially perpendicular tothe backing plate. However, each of the levers may be formed of asynthetic resin material.

[0030] The operable member is preferably constituted by the parkingbrake cable which is connected to a parking operation lever provided inthe passengers' compartment of the vehicle, as in the fourth aspect ofthe invention. However, the operable member may be also constituted, forexample, by a suitable link mechanism. Further, the operable member maybe displaced by an operating force which is applied by the vehicleoperator to the operable member, or alternatively may be displaced by adriving force which is applied by an electric motor or other drivesource to the operable member. In the latter case, the drive source maybe activated in response to a switching operation made by the vehicleoperator, so that the operable member is displaced to be positioned inits operating position by the activation of the drive source.

[0031] The engageable portion defined in the third aspect of theinvention may be constantly held in engagement or contact with the firstlever, or alternatively may be brought into engagement or contact withthe first lever only when the first lever is displaced more than apredetermined amount in a direction perpendicular to a pivot directionin which the first lever is to be pivoted. In the latter case, thereexists a predetermined gap between the first lever and the engageableportion such that the engageable portion and the first lever are notbrought into contact with each other unless the first lever is displacedmore than the predetermined amount in the above-described perpendiculardirection. It is possible to provide the parking brake device of thesecond aspect of the invention with an engageable member whichfunctionally corresponds to the engageable portion, irrespective ofwhether the cover is provided in the parking brake device or not. It isalso possible to provide the parking brake device of the first aspect ofthe invention with the cover having the engageable portion or theengageable member which function to limit the displacement of the brakelever in the direction perpendicular to the pivot direction of the brakelever.

[0032] While the force-acting direction is inclined with respect to theplane parallel to the backing plate by the angle of 5°-30° in the sixthaspect of the invention, the angle of the inclination of theforce-acting direction is not particularly limited, but may be, forexample, 90°.

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The above and other objects, features, advantages and technicaland industrial significance of this invention will be better understoodby reading the following detailed description of the presently preferredembodiments of the invention, when considered in connection with theaccompanying drawings, in which:

[0034]FIG. 1 is a front view showing a moving mechanism and its vicinityin a parking brake device constructed according to one embodiment ofthis invention;

[0035]FIG. 2 is a cross sectional view taken along line 2-2 of FIG. 1;

[0036]FIG. 3 is a cross sectional view taken along line 3-3 of FIG. 1;

[0037]FIG. 4A is a plan view exclusively showing a cover provided in theparking brake device of FIG. 1;

[0038]FIG. 4B is a cross sectional view taken along line 4B-4B of FIG.4A;

[0039]FIG. 4C is a cross sectional view taken along line 4C-4C of FIG.4A;

[0040]FIG. 4D is a cross sectional view taken along line 4D-4D of FIG.4B;

[0041]FIG. 5 is a cross sectional view showing a parking brake deviceconstructed according to another embodiment of the invention, and takenin a line corresponding to the line 3-3 of FIG. 1;

[0042]FIG. 6 is a front elevational view schematically showing aconventional drum-in-disk brake assembly to which the principle of thepresent invention is advantageously applicable; and

[0043]FIG. 7 is a cross sectional view taken along line 7-7 of FIG. 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0044] Referring first to FIGS. 1-4, there will be described a parkingbrake device constructed according to one embodiment of this invention.The same reference numerals as used in the above-described conventionalparking brake device of FIGS. 6 and 7 will be used to identify theelements which are the same as or similar to those in the conventionalparking brake device of FIGS. 6 and 7. No redundant description of theseelements will be provided, in the interest of simplification of thedescription.

[0045]FIG. 1 is a front view showing a toggle-type moving mechanism 60and its vicinity in the parking brake device of the embodiment of thisinvention. FIG. 2 and FIG. 3 are cross sectional views taken along line2-2 and line 3-3 of FIG. 1, respectively. The moving mechanism 60includes a connecting pin 62, and first and second levers 64, 66 whichare superposed on and parallel to each other and which are connected attheir respective end portions with each other through the connecting pin62 such that the first and second levers 64, 66 are pivotable relativeto each other. The connecting pin 62 is held substantially parallel tothe backing plate 10 and extends substantially in the vertical directionas seen in FIG. 1, while the first and second levers 64, 66 extendsubstantially in the horizontal direction as seen in FIG. 1. The firstand second brake shoes 12, 14 are disposed on one of opposite sides ofthe backing plate 10 which is remote from the body of the vehicle, andare held in engagement at the respective end portions with the first andsecond levers 64, 66, respectively.

[0046] The first lever 64, consisting of a single metallic plate andserving as a brake lever, has a recessed portion 68 and an arcuateprotrusion portion 70 in its end portion at which the first lever 64 isconnected with the second lever 66 through the connecting pin 62. Therecessed portion 68 serves as an engaged portion to be engaged with thefirst brake shoe 12. The arcuate protrusion portion 70 serves as acontact portion to be held in contact with the head portion 52 h of acorresponding one of the bolts 52 which serve as a supporting portionfor supporting the moving mechanism 60. The first lever 64 extendsthrough an aperture 74 which is constituted by apertures formed throughthe respective backing plate 10, anchor member 54, dust cover 58 andcarrier 72, such that the other end portion of the first lever 64 ispositioned on the other of the above-described opposite sides of thebacking plate 10, namely, such that the other end portion of the firstlever 64 projects from the aperture 74 toward the body of the vehicle.The first lever 64 has, in a distal end of this other end portion, aconnected portion 76 at which the first lever 64 is connected to aconnecting member 78 of the parking brake cable 40. The second lever 66consists of a single metallic plate which is bent so as to take asubstantially U shape. The first lever 64 is disposed inside the secondlever 66, namely, interposed between two mutually opposed portions ofthe second lever 66 which are opposed to each other as a result of thebending of the single metallic plate, as best shown in FIG. 2. The twomutually opposed portions of the second lever 66 are held in closecontact with each other in the other end portion of the second lever 66which is opposite to the end portion at which the second lever 66 isconnected with the first lever 64 through the connecting pin 62, as bestshown in FIG. 1. The second lever 66 has, in this other end portion, arecessed portion 80 which serves as an engaged portion held inengagement with the second brake shoe 14, and an arcuate protrusionportion 82 which serves as a contact portion held in contact with thehead portion 52 h of a corresponding one of the bolts 52.

[0047] The recessed portion 68 serving as the engaged portion of thefirst lever 64 is positioned between the connecting pin 62 and thebacking plate 10, and the connecting pin 62 is positioned on one ofopposite sides of the first brake shoe 12 which is remote from thebacking plate 10. In this arrangement, when the parking brake cable 40is pulled in the force-acting direction F by an operation of anoperator-controlled operation member (e.g., an operating lever) which isprovided in a passengers' compartment of the vehicle, the parking brakecable 40 applies a tensile force to the first lever 64. With theapplication of the tensile force to the first lever 64, the first lever64 is pivoted about the connecting pin 62 in the counter-clockwisedirection as seen in FIG. 3, whereby the first brake shoe 12 isdisplaced in the outward direction, i.e., in the leftward direction asseen in FIG. 3. The leftwardly displaced first brake shoe 12 is forcedonto an inner circumferential surface of a disk rotor (not shown), forthereby generating a braking force for braking the wheel rotating withthe disk rotor. The connecting pin 62 is displaced relative to the firstbrake shoe 12 in the rightward direction as shown in FIG. 3, by areaction force resisting the outward or leftward displacement of thefirst brake shoe 12. The rightward displacement of the connecting pin 62causes the second lever 66 to be displaced in the rightward direction,whereby the second brake shoe 14 is displaced in the outward direction,i.e., in the rightward direction. The rightwardly displaced second brakeshoe 14 is forced onto the inner circumferential surface of the diskrotor, for thereby generating a braking force for braking the wheelrotating with the disk rotor. The one-dot chain line of FIG. 3 indicatesa position of the connected portion 76 of the first lever 64 when thefirst lever 64 is pivoted to its operating position for activating theparking brake device. It is noted that the aperture 74 consists of anelongated hole whose opening is elongated in the horizontal directionrather than in the vertical direction as seen in FIG. 1, for allowingthe pivot movement of the first lever 64.

[0048] The above-described force-acting direction F is adapted to beinclined with respect to a plane parallel to the backing plate 10 by apredetermined angle α, toward the longitudinally-extending center lineof the vehicle body (i.e., in the upward direction as seen in FIG. 3)away from the above-described one of the opposite sides of the backingplate 10 on which the first and second brake shoes 12, 14 are disposed.The angle α is determined to be not larger than such a degree thatpermits the force-acting direction F to be close to the direction inwhich the brake shoes 12, 14 are to be moved away from each other, i.e.,the horizontal direction as seen in FIG. 3, and at the same time to benot smaller than such a degree that permits the moving mechanism 60(including the first lever 64) to be forced toward the backing plate 10by a certain amount of force, without the moving mechanism 60 beingseparated from the head portions 52 h of the bolts 52 upon activation ofthe parking brake device, i.e., without a risk of reduction in a brakingperformance of the parking brake device. Specifically, the angle α maybe determined to be 5°-30°, for example, about 15° as in the presentembodiment. In this arrangement, a ratio of a braking force (generableby the parking brake device) with respect to a driving or operatingforce (applied to the operable member) is advantageously increased, sothat a relatively large braking force can be generated by even arelatively small driving force, e.g., a relatively small operating forceapplied to an operator-controlled operation member which is provided ina passengers' compartment of the vehicle.

[0049] The parking braking cable 40 is enveloped or accommodated in anouter casing which is fixed to a cable guide 84. This cable guide 84 isfixed to the carrier 72 by the bolts 52 such that the cable guide 84 ispositioned in a predetermined position relative to the carrier 72. Theabove-described force-acting direction F is defined by thispredetermined position of the cable guide 84 relative to the carrier 72.Namely, the force-acting direction F can be adjustable by adjusting thispredetermined position of the cable guide 84 relative to carrier 72.Further, the connected portion 76 (more specifically, a point at whichthe first lever 64 is held in connection or engagement with theconnecting member 78) is positioned such that the force-acting directionF is substantially perpendicular to a straight line connecting theconnected portion 76 and the connecting pin 62. In addition, thedistance from the connecting pin 62 to the connected portion 76 isconsiderably larger than the distance from the connecting pin 62 to theengaged portion 68 (at which the first lever 64 is held in engagementwith the first brake shoe 12), so that the driving or operating force ismultiplied by a high lever ratio, whereby a sufficiently large amount ofbraking force is obtained. In the present embodiment, the distance fromthe connected portion 76 to the connecting pin 62 is at least five timesas large as the distance from the engaged portion 68 to the connectingpin 62.

[0050] A cover 86, which is made of an elastic material, e.g., a rubbermaterial, is provided to cover a space between the first lever 64 andthe aperture 74, namely, a radial spacing defined by and between theperiphery of the first lever 64 and the edge of the aperture 74, whilepermitting the pivot movement of the first lever 64 about the connectingpin 62. FIG. 4A is a plan view exclusively showing this cover 86. FIGS.4B and 4C are cross sectional views taken along line 4B-4B and line4C-4C of FIG. 4A, respectively. FIG. 4D is a cross sectional view takenalong line 4D-4D of FIG. 4B. The cover 86 has a truncated pyramid shapein its entirety, and includes an annular bottom end portion 86 a and anupper end portion 86 b. The annular bottom end portion 86 a has anelongated rectangular cross section whose shape corresponds to anelongated cross sectional shape of the aperture 74, and is gripped byand between the cable guide 84 and the edge of the aperture 74 so as tobe fixed relative to the backing plate 10. The upper end portion 86 b isfixed to a portion of the first lever 64 which portion is adjacent tothe connected portion 76, owing to an elasticity of the elasticmaterial. The upper end portion 86 b has an end face which has aconcavity concaved toward the annular bottom end portion 86 a. Anelongated hole 86 d is formed through a bottom of the concavity, namely,through a ceiling wall of the truncated-pyramid-shaped cover 86. Theelongated hole 86 d has a rectangular cross sectional shapecorresponding to a cross sectional shape of the first lever 64. Anannular protrusion 86 d, which is located in the periphery of the endface of the upper end portion 86 b, serves to enable the upper endportion 86 b to be deformed or displaced together with the pivotmovement of the first lever 64. That is, the upper end portion 86 b issufficiently displaceable in the direction of the pivot movement of thefirst lever 64, principally owing to elastic deformation of the annularprotrusion 86 d.

[0051] A pair of protrusion 86 e is formed on an inner circumferentialsurface of a longitudinally intermediate portion of the annular bottomend portion 86 a of the cover 86, as best shown in FIG. 4B. Each of theprotrusions 86 e has a generally trapezoidal cross sectional shape, andprotrudes inwardly from the inner circumferential surface of thelongitudinally intermediate portion of the annular bottom end portion 86a. As is apparent from FIG. 2, each of the protrusions 86 e has a distalend which is located inwardly of the inner circumferential surface ofthe aperture 74. That is, the distance from the periphery of the firstlever 64 to the distal end of each of the protrusions 86 e is smallerthan the distance from the periphery of the first lever 64 to anyportion of the inner circumferential surface of the aperture 74. Theprotrusions 86 e serve as an engageable portion which is engageable withthe first lever 64, for limiting movement of the first lever 64 in adirection perpendicular to a pivot direction in which the first lever 64is to be pivoted. Each of the protrusions 86 e is elongated in the pivotdirection, as shown in FIGS. 3 and 4B, and has a length sufficient topermit the first lever 64 to be engageable with the protrusion 86 e inany pivoted position of the first lever 64. As shown in FIG. 2, therenormally exists a predetermined gap between the first lever 64 and eachof the protrusions 86 e. When the first lever 64 is displaced or movedin the above-described perpendicular direction more than a predetermineddistance, the first lever 64 is brought into engagement with one of theprotrusions 86 e, whereby the first lever 64 is prevented from beingbrought into abutting contact with a metallic component such as thebacking plate 10.

[0052] In the parking brake device constructed according to theembodiment of the invention, the first lever 64 extends through theaperture 74 formed through the backing plate 10 and the other memberssuch that the connected portion 76 of the first lever 64 is positionedon the above-described other of the opposite sides of the backing plate10, namely, such that the connected portion 76 of the first lever 64projects from the aperture 74 towards the body of the vehicle. Thisarrangement facilitates an operation for connecting the parking brakecable 40 to the first lever 64, and also makes it possible to eliminatea conventionally required guiding member as shown in FIG. 7, leading toreduction in the number of the required components of the parking brakedevice and consequent reduction in the cost of manufacture of thedevice.

[0053] Further, the positioning of the connected portion 76 of the firstlever 64 on the above-described other of the opposite sides of thebacking plate 10 is effective to increase a degree of freedom indetermining the force-acting direction F in which the driving oroperating force applied through the parking brake cable 40 acts on thefirst lever 64, thereby making it possible to install the parking brakedevice in various types of vehicles. Since the angle α of theinclination of the force-acting direction F is set to be about 15°,namely, the force-acting direction F is adapted to be close to thedirection in which the first and second brake shoes 12, 14 are movableaway from each other, it is possible to reduce a sliding resistanceacting between the head portions 52 h and the contact portions 70, 82,thereby increasing the above-described ratio of the braking force withrespect to the driving force. Further, since the force-acting directionF is inclined with respect to the plane parallel to the backing plate 10by at least 5° toward the longitudinally-extending center line of thevehicle body, the moving mechanism 60 including the first lever 64 isforced toward the backing plate 10 by a certain amount of force withoutthe moving mechanism 60 being moving away from the backing plate 10 uponactivation of the parking brake device, i.e., without a risk ofreduction in a braking performance of the parking brake device.

[0054] Further, in the present embodiment of the invention, theconnected portion 76 (more specifically, a point at which the firstlever 64 is held in connection or engagement with the connecting member78) is positioned such that the force-acting direction F issubstantially perpendicular to a straight line connecting the connectedportion 76 and the connecting pin 62. In addition, the distance from theconnecting pin 62 to the connected portion 76 is considerably largerthan the distance from the connecting pin 62 to the engaged portion 68(at which the first lever 64 is held in engagement with the first brakeshoe 12), so that the driving or tensile force is multiplied by a highlever ratio, whereby a sufficiently large amount of braking force isobtained.

[0055] Still further, the engageable portion in the form of the pair ofprotrusions 86 e is formed integrally with the other portion of therubber-made cover 86 which covers the space between the periphery of thefirst lever 64 and the edge of the aperture 74, so that backlashmovement of the first lever 64 in the direction perpendicular to thepivot movement direction can be limited by engagement of the protrusions86 e with the first lever 64. Owing to this arrangement, it is possibleto prevent abutting contact of the first lever 64 with the edge of theaperture 74, i.e., abutting contact of metallic members with each other,for example, when the vehicle body is vibrated during running of thevehicle. Thus, generation of unpleasant noise which would be caused inthe event of the abutting contact of the metallic members isadvantageously avoided.

[0056] While the angle α of the inclination of the force-actingdirection F with respect to the backing plate 10 is about 15° in theabove-illustrated embodiment, the angle α is not particularly limited,but may be changed suitably depending upon, for example, the type ofvehicle in which the parking brake device to be installed. FIG. 5illustrates a parking brake device constructed according to anotherembodiment of the invention in which the angle α is adapted to be about90°. In this parking brake device of FIG. 5, a first lever 90 serving asthe brake lever has a connected portion 92 and a curved portion 94 inwhich the first lever 90 is curved by about 90°. The first lever 90extends through the aperture 74 such that the curved portion 94 as wellas the connected portion 92 is positioned on the side of the backingplate 10 which is remote from the brake shoes 12, 14. The parking brakedevice of this embodiment is activated by pulling the parking brake 40which is engaged with the connected portion 92 of the first lever 90, inthe force-acting direction F which is substantially perpendicular to thebaking plate 10.

[0057] While the presently preferred embodiments of the presentinvention have been illustrated above, it is to be understood that theinvention is not limited to the details of the illustrated embodiments,but may be embodied with various other changes, modifications andimprovements, which may occur to those skilled in the art, withoutdeparting from the spirit and scope of the invention defined in thefollowing claims.

What is claimed is:
 1. A parking brake device for a vehicle, comprising:a backing plate which is fixed to a body of the vehicle such that saidbacking plate is held substantially perpendicular to an axis of a wheelof the vehicle; first and second arcuate brake shoes which are disposedon one of opposite sides of said backing plate such that said first andsecond arcuate brake shoes are movable toward and away from each other;a moving mechanism which is positioned between the first and secondarcuate brake shoes and which includes a pivotable brake lever, saidmoving mechanism moving said first and second arcuate brake shoes awayfrom each other when said brake lever is pivoted in a predetermineddirection; and an operable member which is connected to said brake leverand which is operable by an operator of the vehicle to pivot said brakelever in said predetermined direction, wherein said brake lever has aconnected portion at which said brake lever is connected to saidoperable member, and wherein said brake lever extends through anaperture which is formed through said backing plate such that saidconnected portion is positioned on the other of said opposite sides ofsaid backing plate.
 2. A parking brake device for a vehicle, comprising:a backing plate which is fixed to a body of the vehicle such that saidbacking plate is held substantially perpendicular to an axis of a wheelof the vehicle; first and second arcuate brake shoes which are disposedon one of opposite sides of said backing plate such that said first andsecond arcuate brake shoes are movable toward and away from each other;a moving mechanism including first and second levers which are engagedwith said first and second arcuate brake shoes, and which are connectedwith each other through a connecting pin that is held substantiallyparallel to said backing plate, such that said first and second leversare pivotable relative to each other about said connecting pin, saidmoving mechanism moving said first and second arcuate brake shoes awayfrom each other when said first lever is pivoted about said connectingpin in a predetermined direction; and an operable member which isconnected to said first lever and which is operable by an operator ofthe vehicle to pivot said first lever about said connecting pin in saidpredetermined direction, wherein said first lever has a connectedportion at which said first lever is connected to said operable member,and wherein said first lever extends through an aperture which is formedthrough said backing plate such that said connected portion ispositioned on the other of said opposite sides of said backing plate. 3.A parking brake device according to claim 2, further comprising a coverwhich is made of an elastic material, and which covers a space betweensaid first lever and said aperture while permitting said first lever tobe pivoted about said connecting pin, wherein said cover has anengageable portion which is engageable with said first lever, forlimiting a movement of said first lever in a direction perpendicular tosaid predetermined direction.
 4. A parking brake device according toclaim 2, wherein said operable member is a parking brake cable which isconnected at one of opposite end portions thereof to said first leverand which is connected at the other of said opposite end portions to anoperating lever provided in a passengers' compartment of the vehicle. 5.A parking brake device according to claim 2, wherein said first lever isengaged at an engaged portion thereof with said first arcuate brakeshoe, and wherein a distance between said connected portion and saidconnecting pin is at least five times as large as a distance betweensaid engaged portion and said connecting pin.
 6. A parking brake deviceaccording to claim 2, wherein said operable member applies a force tosaid first lever such that said force acts on said first lever in aforce-acting direction that is inclined with respect to a plane parallelto said backing plate by an angle of 5°-30° toward alongitudinally-extending center line of the body of the vehicle.
 7. Aparking brake device according to claim 2, wherein said operable memberapplies a tensile force to said first lever such that said tensile forceacts on said first lever in a force-acting direction that is inclinedwith respect to a plane parallel to said backing plate by an angle of5°-30° in such a direction that causes said first lever to be forcedtoward a longitudinally-extending center line of the body of the vehiclewhen said tensile force is applied to said first lever by said operablemember.
 8. A parking brake device according to claim 6, wherein saidconnected portion is positioned such that said direction issubstantially perpendicular to a straight line connecting said connectedportion and said connecting pin.
 9. A parking brake device according toclaim 2, wherein said operable member applies a force to said firstlever such that said force acts on said first lever in a force-actingdirection that is substantially perpendicular to a plane parallel tosaid backing plate.